Why didn't Pharaoh Killed Musa As?

> And the eminent among the people of Pharaoh said, "Will you leave > Moses and his people to cause corruption in the land and abandon you > and your gods?" [Pharaoh] said, "We will kill their sons and keep > their women alive; and indeed, we are subjugators over them." Quran 7:127 In this verse we can clearly see pharaoh had the chance to kill Musa As. Instead he totally ignored his people's advice and told them to kill the Children of Israel. **My question is nothing was preventing pharaoh to kill Musa As. But he didn't, it seems he has some soft side for Musa As. Any scholar said anything about this. Any reason for pharaoh being soft towards Musa As?**